Thanks for your very fast response.
For clarity, the rental property was never my main residence. At the financial mediation in 2009, ownership of the rental property was transferred to 'joint names' (previously in the sole name of my wife) as part of the financial settlement, on the understanding that as and when sold, the balance after costs would be equally divided. We now intend to sell and divide the balance from the sales after repaying the mortgage and deducting the selling cost.
From your reply, it looks as if we will be separately liable for the CGT on our individual portions (circa £60K each gross) at the appropriate rate. Am I correct.